Warning.... Kappalite 3015 NOT designed for Bass!

[discreet]

[quote name='ShergoldSnickers' timestamp='1380982798' post='2233104']
I don't think any of us realise what a complex subject speaker/cabinet acoustics is until you start to delve.
[/quote]

Quite. You only have to look at Bill's plans for the Jack 12 (for example) to see that speaker cabs are not just boxes.

[Phil Starr]

I hope this comes out. I've attached a file from WinISD with three plots of a Kappalite in three boxes.

All three plots show the cone excursion with 450W going through the speaker.

The yellow line is a 'standard cab' generated by WinISD but similar to the 'large vented box' on the Eminence website.

The pink line is a smaller cab tuned slightly lower to improve low frequency power handling.

The Blue like is the larger cab but tuned to the 'wrong' frequency to show the effect of an 'untuned' cab.

You can see they are all the same basic shape. The excursion rises as the frequency falls, then there is a dip in excursion as the port kicks in with the deepest point right on the port tuning frequency. Below the tuning point the excursion rises rapidly reaching dangerous levels at subsonic frequencies. This pattern is shared by all ported cabs.

The crucial points are 6mm excursion where the Kappalite starts to distort and 11mm excursion where it starts to destroy itself.

You can see that the Kappa in the large box (yellow line)can't handle 450W without distorting even in it's pass range. Eminence themselves recommend 300W as the maximum power. Below 38Hz it will exceed 11mm and be destroyed. You need the bigger box though for a flat frequency response. In the smaller box (pink line) the Kappa gives little or no distortion until the port unloads and stays below the 11mm destruction point until 30Hz. The blue line shows the effect of the wrong (too high) tuning; the 11mm destruction point is reached at about 42Hz which is just about low E. So if you use a Kappalite in a poorly tuned large cab with the full recommended power it will fail.

I hope this helps the non techie. All the experts on here already know this. I have some thoughts on what this means about how speakers should be advertised and what it means for customer service, but I want this to be purely factual so I'll stop here.

[brensabre79]

[quote name='Salt on your Bass?' timestamp='1380979571' post='2233057']
I think if this thread highlights anything it's that you can't just Chuck any old speaker in any box and expect it to be ok.
[/quote]
+100

Every time I see a thread on here asking "can i stick driver X in my old brand Y cabinet as a replacement" I cringe a little. The answer is usually "possibly". Always, always run a simulation using WinISD or similar before shelling out ££s for a driver.

I have to say, I have dealt with Eminence directly in the past and found them to be very helpful and informative, even if they did send me to Blue Aran to actually buy the product, the technical support peeps were more than happy to advise.

You can't expect a distributor to know such detailed parameters as these, and ultimately if you don't know what you're doing with these things the safest way is always to go to the manufacturer for a like-for-like replacement.

[Guest bassman7755]

[quote name='Mr. Foxen' timestamp='1380846327' post='2231580']
Important thing is: the driver needs to be in an appropriately tuned enclosure. compression and bandpassing are bodges to get around the problems caused by not doing this.
[/quote]

A high pass of say 30hz cant hurt though and I think most "bass" amps have something like this. You have to be a bit more careful with "pro" PA amps as many will go almost down to DC - before I configured the high pass setting on my old QSC I could push a string slowly down towards the pickup and watch the speaker cones track the movement !.

[Mr. Foxen]

[quote name='brensabre79' timestamp='1381136105' post='2234640']
You can't expect a distributor to know such detailed parameters as these
[/quote]

Distributors sometimes hand out advice as if they know and understand both the parameters, and the situation, and that's where there is a problem.

[quote name='bassman7755' timestamp='1381137600' post='2234670']
A high pass of say 30hz cant hurt though and I think most "bass" amps have something like this. You have to be a bit more careful with "pro" PA amps as many will go almost down to DC - before I configured the high pass setting on my old QSC I could push a string slowly down towards the pickup and watch the speaker cones track the movement !.
[/quote]

Ideally, high pass should be configured bearing the box properties in mind, aiming to cut off about the place where the speaker is unloading, otherwise there can still be the danger gap. Stuff gets worse as you go lower, but still can not be good before its that low.

[Billy Apple]

[quote name='Bill Fitzmaurice' timestamp='1380984976' post='2233126']
I'm well aware that it can be done. My point is that it shouldn't be, there's nothing to be gained, and potentially a driver to be lost.
[/quote]

My point is not whether it can or can't be done, my point is that there are differences in opinion. In this case, one from a very knowledgeable chap such as yourself, and another from the manufacturer. For my money, I think the OP should be speaking to Eminence.

[alexclaber]

A lot of bass amps have some kind of highpass filtering, whether it be in the form of a PA-style steep highpass filter in the 30-40Hz region or a more gentle LF roll-off, often starting higher up. I've measured or seen plots of various Trace and GK heads gently rolling off from around 80Hz, Markbass and Genz steeply at 40Hz, TC surprisingly steeply from about 80Hz, etc. Both Mesa and SWR don't tend to have any filtering, so they go very low and cause woofers to wobble back and forth. The SWR Grand Prix preamp did have a switchable 30Hz highpass, which was a nice touch that was missing on their heads.

An interesting example of how much difference a filter can have is using my Avalon U5 rig with a passive bass (some active basses already have filtering) and my QSC PLX. The QSC has a 5Hz subsonic filter whilst the U5 is DC-coupled. The QSC also has 30Hz and 50Hz switchable filters - the former stops a lot of cone wobble with no change to the tone. The 50Hz filter removes almost all visible cone movement until you're playing incredibly loud but you can hear how it tightens up the sound and also makes the sound smaller. Bear in mind that if a filter is a 30Hz filter, that means it's 3dB down at 30Hz, not that it starts working at that frequency, so for the best balance of tone and loudness, if you're not going through a big PA, then filters are best off being on the lower side, at ~25-35Hz, so they don't mess with your tone.

There is a risk that if you put too much effort into reducing cone excursion through the use of filtering and limiting that you'll be able to raise the average power level dangerously high without hearing the warning sound of increased distortion caused by over-excursion. Also, bear in mind that the less a loudspeaker moves, the lower its thermal power handling will be because that movement literally pumps the hot air out of the motor.

[Bill Fitzmaurice]

[quote name='Billy Apple' timestamp='1381150371' post='2234953']
My point is not whether it can or can't be done, my point is that there are differences in opinion. In this case, one from a very knowledgeable chap such as yourself, and another from the manufacturer. For my money, I think the OP should be speaking to Eminence.
[/quote]That depends on who at Eminence. For the most part when you email Eminence for advice you deal with a customer service rep, who gives advice based on a drop-down menu that they have of stock answers to what amount to FAQs. These people aren't engineers. They will have a far higher degree of product expertise than a retailer, but they don't make their livings designing either transducers or enclosures. Not that there aren't engineers at Eminence, but said engineers work in the engineering department, not customer service. You will not be put in contact with them, or even know their names, unless you are an industry professional, like myself or Alex.
That doesn't mean that one needs the advice of an industry professional. There are certainly many amateurs quite capable of using speaker modeling software able to give definitive advise on how a certain driver will function in a specific cabinet. That advise could include specific details of the need to high pass at a specific frequency and to limit amplifier output to a specific voltage swing to insure that the driver cannot be harmed. You won't get that from Eminence's customer service department. The closest you'll get to that is if you look at their published plans for their drivers, which do come from their engineering department. But even that information can be duplicated by anyone with modeling software, and the knowledge of how to use it.

[Billy Apple]

[quote name='Bill Fitzmaurice' timestamp='1381159760' post='2235154']
That depends on who at Eminence. For the most part when you email Eminence for advice you deal with a customer service rep, who gives advice based on a drop-down menu that they have of stock answers to what amount to FAQs. These people aren't engineers. They will have a far higher degree of product expertise than a retailer, but they don't make their livings designing either transducers or enclosures. Not that there aren't engineers at Eminence, but said engineers work in the engineering department, not customer service. You will not be put in contact with them, or even know their names, unless you are an industry professional, like myself or Alex.
That doesn't mean that one needs the advice of an industry professional. There are certainly many amateurs quite capable of using speaker modeling software able to give definitive advise on how a certain driver will function in a specific cabinet. That advise could include specific details of the need to high pass at a specific frequency and to limit amplifier output to a specific voltage swing to insure that the driver cannot be harmed. You won't get that from Eminence's customer service department. The closest you'll get to that is if you look at their published plans for their drivers, which do come from their engineering department. But even that information can be duplicated by anyone with modeling software, and the knowledge of how to use it.
[/quote]

Well, the chap's signature says technical support, so read into that what you will. BTW, this is what he had further to say on the subject...

[font=Calibri, sans-serif][size=4]You can cut all the way to the cone, as the cone glue is a lot stronger than the gasket glue. However, it would be much safer to cut it off even with the frame, if that’s all you need to remove.[/size][/font]

Any-hoo, I stand by my belief that it's a good idea to contact the manufacturer.

[Ian Savage]

[quote name='Phil Starr' timestamp='1381131615' post='2234579'] I hope this comes out. I've attached a file from WinISD with three plots of a Kappalite in three boxes. [snip] [/quote]

Really interesting to see Phil, thanks for that!

[Mr. Foxen]

I've been put through to the design engineer when I called Ashdown (Dave Green), someone less used to dealing with gruff Northern amp engineers might be less than impressed with his customer handling skills. Stuff like 'Who the f*ck" gave you my number?' will do that.

[skidder652003]

[quote name='Mr. Foxen' timestamp='1381164769' post='2235244']
I've been put through to the design engineer when I called Ashdown (Dave Green), someone less used to dealing with gruff Northern amp engineers might be less than impressed with his customer handling skills. Stuff like 'Who the f*ck" gave you my number?' will do that.
[/quote]

[R Baer]

[quote name='alexclaber' timestamp='1380620797' post='2227845']
The driver in question is excellent for bass guitar. The damage is a clear case of both excursion and thermal overpowering. Most cheap bass cabs are tuned too high which means they'll unload on low note fundamentals. Having your volume control at 65% does not mean you're not using full power - you could easily hit full power with all your gain controls at 30% if you have a fairly hot bass and pluck hard. It clearly isn't a case for a warranty claim but Blue Aran's reasoning is incorrect. We have hundreds of 3015 in use in Compacts and Super Fifteens and none have ever failed - we've had the odd manufacturing related warranty return (misaligned cone, dustcap unglueing, etc) but no-one has ever blown one. Ironically we have far fewer 3015LFs out there (in Big Ones and Dubsters) but we've had two blown (both thermal failure with ~1000W amps).
[/quote]

+1 The 3015 is a great driver for a bass cabinet. Per the Eminence website "Recommended for vented professional audio enclosures for full range...." Full range would include a bass cab as well. Pretty much any driver can be pushed too hard into over-excursion, or fed enough power to burn out the voice coil. In my experience, there is a tendency for the term "super 12" or "super 15" to be taken as meaning these cabinets are capable of handling anything you can throw at them. Regardless of how well they perform, every cab does in fact has it's limits.

Edited October 7, 2013 by R Baer

[Phil Starr]

[quote name='alexclaber' timestamp='1380620797' post='2227845']
The driver in question is excellent for bass guitar. The damage is a clear case of both excursion and thermal overpowering. Most cheap bass cabs are tuned too high which means they'll unload on low note fundamentals.
[/quote]
[quote name='Bill Fitzmaurice' timestamp='1380630582' post='2228069']
+1. As is the case with any and all drivers it must be loaded into a cab that is compatible with its specs. If one is to push it to maximum output the amp must at the very least be appropriately high passed, if not limited to the driver's safe operating voltage swing.
In terms of performance the 3015 is on par with an Aston Martin.
[/quote]
[quote name='R Baer' timestamp='1381186373' post='2235685']
+1 The 3015 is a great driver for a bass cabinet. Per the Eminence website "Recommended for vented professional audio enclosures for full range...." Full range would include a bass cab as well. Pretty much any driver can be pushed too hard into over-excursion, or fed enough power to burn out the voice coil. In my experience, there is a tendency for the term "super 12" or "super 15" to be taken as meaning these cabinets are capable of handling anything you can throw at them. Regardless of how well they perform, every cab does in fact has it's limits.
[/quote]

So it is absolutely clear that this speaker is a great choice for bass, Alex Claber, Bill FitzMautice and Roger Baer all agreeing, and full range does mean including bass. it is also clear that the damage was caused by over excursion from the photo's provided by Blue Aran.

The big question then is: was this a suitable cab? To settle this I modelled the cab with WinISD using data from the Warwick website. The cab is just over 140l and tuned to 35Hz.

The frequency plot is poor, the cab rolls off starting at 500Hz and is 6db down at bottom E. This is due to over damping from too large an air mass. A smaller cab would give much better bass. the crucial plot is the excursion plot however. If excursion is in excess of 11mm within the pass band then the failure is due to the cab design. If it is not, the failure is due to something else.

I've attached the plot. This is with 450W power. The Warwick trace is in blue/green the other is Eminence's cab, similar in size to the Compact. You can see the unsuitability of the larger cab, the Compact sized cab keeps excursion within 6mm down to 35Hz the Warwick cab allows the excursion to rise to 10mm in the 'critical 60Hz region' meaning the bass will be distorted due to the misalignment of the port, which is tuned too low for this speaker. Both speakers exceed the damage excursion below 30Hz, though the Warwick is slightly better in this area than the smaller cab.

This wasn't by any means a good choice of cab, it is designed for a speaker with a lower Fs and less well damped than the 3015, a smaller cab tuned to 45Hz would have been better. But, this speaker, in this cab using the full power of the SWR should not have been hitting the back of the magnet as it seems to have done. I guess it was out of manufacturing tolerance.

Edited October 12, 2013 by Phil Starr

[Wimpy]

Hey guys...what about this baby? [b]BEYMA 15MI100[/b]...well it's twice heavy than Kappalite, but maybe similar or better quality.

Edited May 6, 2015 by Wimpy

[skidder652003]

chr*ist don't resurrect this post please, I still have nightmares about it!

[stevie]

I love it when an ancient thread suddenly reappears out of nowhere...... The answer to the question though, it that the Beyma is not ideal for bass guitar: it was designed for midrange efficiency more than anything else.

[Wimpy]

thanks ;-)